Читать книгу World History For Dummies - Peter Haugen - Страница 36

Earth formed about 4.5 billion years ago, or so the astrophysicists say. My mind balks at the thought of such an expanse of time.

I do better starting with recent times, here meaning the many thousands of years that people have lived on Earth. Recent is a relative term. The modern human species — meaning people who are anatomically the same as you — may not be much more than 100,000 years old, although scientific estimates vary. And paleoanthropologists (human-fossil nerds) say that human beings didn’t start acting fully “human” until more recently. Humanity turned a corner roughly 60,000 years ago, when stone tools got more sophisticated, and people began carving patterns into rocks and bones, using charcoal to make exquisite cave paintings, and inventing rafts to cross water. These artistic expressions and engineering tasks mark them as being more like you and less like earlier models of the hominid (humanlike) family. Many scholars refer to members of our species who lived 30,000 years ago as being fully modern. In that usage, modern, like recent, is a relative term. Obviously, it doesn’t mean people who share TikTok videos. We can take it to mean people who behaved a bit more like us and less like earlier prehistoric humans had.

You’ve probably seen the familiar illustration showing successive ancestor species marching single file, ever more upright and less hairy, toward modern humanity. Evolution didn’t happen that way, however. Evolution is rarely neat. Different kinds of more-or-less humanlike animals lived at the same time. Many were genetic dead ends and died out, although the genetic record reveals that other, related types of humans — including Neanderthals and Denisovans — interbred with our own ancestors, so in that way, they are us. All earlier hominids are extinct … unless you buy the idea that Sasquatch (Bigfoot) and Yeti (the Abominable Snowman) are your reclusive country cousins.

As a species, modern humans are young, and again, I’m speaking relatively. Homo erectus — if not your direct ancestor, at least a close relative — was on Earth much longer than modern people have been here. Homo erectus lived from about 1.7 million years ago to perhaps as recently as 108,000 years ago.

If you think of the entire time since the emergence of hominids, perhaps 4 million years ago, to the present day as a single 24-hour day, Homo erectus lasted more than 8 hours. On that scale, modern humans have been here for about 15 minutes.